Neat. It reminds me of RIchard D James (AKA Aphex Twin) who set up an old Sinclair ZX81 and changed the background hue on his TV rapidly. This caused interference to the audio circuit which, when he altered the speed of colour change, he could produce noise which approximated actual notes. The ZX81 didn't have any sound output nominally. He won some sort of prize as a schoolboy for this feat.

Quote:

Richard claims to have produced sound on a Sinclair ZX81 (a machine with no sound hardware) at the age of 11:

When I was 11, I won 50 pounds in a competition for writing this program that made sound on a ZX81. You couldn't make sound on a ZX81, but I played around with machine code and found some codes that retuned the TV signal so that it made this really weird noise when you turned the volume up.